Probabilistic Mesomechanics for High Cycle Fatigue Life Prediction

1999 ◽  
Vol 122 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Robert G. Tryon ◽  
Thomas A. Cruse
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Crack Nucleation ◽  
Fatigue Loading ◽  
Material Behavior ◽  
Analytical Models ◽  
Cycle Fatigue ◽  
Prediction Capability ◽  
Fast Fracture

This paper presents an analytical modeling approach to characterize and understand high cycle fatigue life in gas turbine alloys. It is recognized that the design of structures subjected to fatigue cannot be based on average material behavior but that designs must consider −3σ or some other appropriate extreme value (tail of the distribution) loading and/or material properties. Thus, a life prediction capability useful in a design application must address the scatter inherent in material response to fatigue loading. Further, the life prediction capability should identify the key micromechanical variables that are critical in the tail of the materials durability distribution. The proposed method addresses the scatter in fatigue by investigating the microstructural variables responsible for the scatter and developing analytical and semi-analytical models to quantitatively relate the variables to the response. The model is general and considers the entire range of damage accumulation sequences; from crack nucleation of the initially unflawed structure to final fast fracture. [S0094-4289(00)01302-5]

Very High Cycle Fatigue Testing under Spectrum Loading for Endurance Limit Structural Design

2020 ◽  
Vol 65 (1) ◽  
pp. 1-7
Author(s):  
David T. Rusk ◽  
Robert E. Taylor ◽  
Bruce A. Pregger ◽  
Luis J. Sanchez
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Crack Nucleation ◽  
Peak Stress ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

A program has recently concluded that generated fatigue test data for the influence of a rotorcraft main rotor blade root bending spectrum (Helix) on the crack nucleation mechanisms in 7075-T651 aluminum. High-frequency tests were performed that generated spectrum fatigue failures out to nearly 109 cycles. Fractographic examination showed a distinct change in crack nucleation from slip initiated to inclusion-initiated cracking as the spectrum peak stress level was increased. Spectrum life predictions were made using three different baseline constant-amplitude S-N curves, one using a traditional rotorcraft original equipment manufacturer fitting methodology, one using the high-cycle fatigue (HCF) portion of a strainlife curve, and one that was fitted to S-N data with test lives out to 3×108 cycles. The spectrum life prediction using the S-N curve that properly modeled material behavior in the very high cycle fatigue regime provided a good correlation to the spectrum fatigue test data. Predictions using the other S-N curves were highly conservative.

Fatigue Life Prediction of Corroded Reinforced Concrete Beams under Repeated Loads

2011 ◽  
Vol 255-260 ◽  
pp. 504-508
Author(s):  
Li Song ◽  
Zhi Wu Yu
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Test Results ◽  
Cycle Fatigue ◽  
Repeated Loads

The behavior of materials under repeated loading has been examined, but extended studies are more and more needed especially for damaged reinforced structures such as bridges, where high-cycle fatigue phenomena and corrosion can be significant. In the present paper, a theoretical model based on fatigue performance of materials and stress analysis for cross-section is proposed in order to analyze the fatigue damage of corroded reinforced concrete beams under repeated loads. Further, fatigue life is predicted by applying this method, and the method is evaluated by test results.

Prediction of Fatigue Life of Structural Steel S355-J2G3 with SK Critical Plane Model

2018 ◽  
Vol 774 ◽  
pp. 504-509
Author(s):  
A.S. Cruces ◽  
Pablo Lopez-Crespo ◽  
S. Sandip ◽  
Belen Moreno
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Multiaxial Fatigue ◽  
Stress Effect ◽  
Critical Plane ◽  
Plane Model ◽  
Data Set ◽  
Proposed Model ◽  
Prediction Capability

The present work assesses the fatigue life prediction capability of a recently proposed critical plane model. For this study, multiaxial fatigue data of S355-J2G3 steel were used; in-phase and 90o out-of-phase sinusoidal axial-torsional straining from 103 to 106 cycles, so it was possible to evaluate the model at low and high cycle fatigue, as well as the hardening effect. The damage parameters considered in this paper include the effect of hardening, mean shear stress effect and the effect due to interaction of shear and normal stress on the critical plane. A comparative evaluation of well accepted models (Wang-Brown, Fatemi-Socie and Liu 1 and 2) with the new recently proposed model (Suman-Kallmeyer) is done. The ability of the different models to predict the fatigue life for large and diverse load data set are discussed.

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